Electric motor



2l Sheets-sheet G. H. PoTH ELECTRIC MOTOR Filed 0G13. 24, 1921 Feb. 10, 1925.

Feb, 1@ m25. @525,691

G. H. PoTl-i,I ELECTRIC' MOTOR Filed Oct. 24, 1921 2 Sheets-Sheet 2 Patented Feb.' v10, 1925.

l'UNITED ,STATES PATENroFFlcE.

GEORGE HENRY POTH, 0F CINCINNATI, OHIO, ASSIGNOR TO THE HISEYWOLF MA- CHINE COMPANY, OF CINCINNATI, OHIO, A PARTNERSHIP CONSISTING O'F WALTER J. FRIEDLANDER AND JOSEPH A. FRIEDLANDER.

ELECTRIC MOTOR.

Application led October 2`4, 1921. Serial No. 509,900.

To all whom t may concern.'

Be it known that I, GEORGE HENRY Po'rH, formerly a subject of the Emperor' of Germany, who have taken out my first papersl for citizenship in the United States, and a resident of Cincinnati, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Electric Motors, of which the. following is a. f,ull,'clear, and exact description', reference being had tothe accompanying drawings, forming part of this specification.

. My invention relates to improvements in electric motors, chiefly from the point of view of the mechanical parts thereof, and

- without regard to the windings, nature of ing which has its'own take-up for endwise brushes, stator and armature parts.

Among other objects of my invention is the provision of vbearings for the shafts of electric motors which have outer raceways that are free to slide' but not rotate, and which can thus be kept under spring tension. By this means I obtain, in connection with a motor case and drill case, a true bearing for the shafts .in a nrotor without having to rely on accurate machining, anda bear d play,and for expansion and 'contraction of shaft, and the like.

Another object of my invention is'to provide for easy assembly of parts and a fan which does not interfere with the Wired parts of the motor.

F urthermore, in connection with the casing and assembly of. parts I provide for air passages which bring cold air over the commutator and thence through the motor and maintain anair pressure behind the fan, which holds flowing oil in the gear box and shaft bearings.

It will benoted that my invention is shown as applied to a motor for portable electric tools, but it will be understoodthat various features of my invention are applicable to electric motors in general and more particularly' 'to small electric motors of the type used in electric tools:

I accomplish the objects above set forth and other advantages to be noted by that certain construction and arrangementof specifically through a motor, as used in electric tools.

Figure 2 is aI detail bottom plan View of the back cap of the device partly broken away.

Figure 3 is a section on the line 3-3 of Figure 4.

Figure 4.- is an end 'elevation of the front cap of the device. l

The motor casing, of tubular form, as at 1. is shown with a handle 2 attached at the lower side, and a switch device 3, also serving as a handle, attached at the upper side. Thiscasing has ribs 4 located about the interior thereof to form air passages between them, and the field member 5 is set into the casing, bearing on the ribs, and at the upperend held in place by a setlscrew 6, that passes through a boss. 7, which also spaces the field member away from the inner wall of the casing.

On the ends of the casing are mounted the front cap 8 and the back cap 9, which will be described more in detail below. The

rotor or armature 10 with its shaft 11 is Set intothe casing inside of the field, and the shaft supported in bearings in the .back cap and in a gear .plate 12, which in this'case is inserted between the-casing and the front cap. y

On the shaft is' the commutator 13,` and the brushes (not shown) are mounted on a suitable plate 14. This plate is set against the flange 15 'at the back end of thecasing j to engage over the rib 16 on the casing` liange.v By this construction the brush Aholder plate may be clamped tightly position in the casing.

i "Screwed onto the armature shaft vis a fan "122 which is preferably cast, and due to the nieans of making and mounting it, does not have to be drilled. The fan has central openings, which are quite large, and' its in# ner rim 23 is set in closejuxtaposition to a peripheral rib 24 on the inside of the causing l, While itsouter rim lies Well short ofl the gear plate.

AIn the gear-plate' visa suitable ball-bears 1 ing, the inner race25 of which takes the thrust of the armature shaft against a shoul` der 26 thereon. The outer race 27. is pressed V tightly into the gear platev to clear the fan hub, which hub wipes a-felt Washer 28 that' lies in the boss 29 of the gear plate that houses the bearing.

The nut 3Q on the end `fof the shaft protruding through the inner bearing raceway.-

engages the inner racewa-y on its outer edge, and the shaft itself hasa pinion 31 thereon,- which lies Within the-.front cap.

The gearplate isspaced away from the.

` outer portion of the fan, except vadjacent operation ofthe motor the 'air ,drawnthe central boss 29, so as to leave a space or chamber 32 into which the fan can force air. The front cap, as willbe noted, serves as'a housing for various bearings, shafts andgears, and one-of the features of great advantage in my' invention is that during through the casing by the fan provides suffi'- cient pressure in the chamber to prevent I' flowing lubricant from getting .backint'othe ,e5-

yto prevent such a flow when the' motor is' wired parts. The felt onthe fan hub acts idle, but during operation great difficulty is found in motors of the character described min providing proper lubrication forv the gears without subjecting thev wired parts to the 'danger'of' becoming covered with lubricant.l vThis my air arrangement effectively prevents.

' Referring next to the manner of introduc-l tion ofl air into the interior of the rear of the casing and the passageways out-from f the front, it will be noted that the back cap is made with recesses 33 formed around its y edge, so that when it is screwed down on the main casing in the usual manner, the air can pass through said recesses into, theinterior of the cap. The cap is shown as car- *rying a breast plate or handle 34, this being I .I a familiar appliance inconnection with port-4 able electric tools, such as ydrills and the like, and in' order to adjust the brush plate" a door 35 is provided having formed thereon coY va tongue V35a and the casing flange provided with an extra lip 3 6,thereby providing a socket into which the tongue may fit. This door is held down -by a screw 36a.

When the air enters into the cap it is i drawn through the hole left in the brush holder plate for commutator clearance and thence into the interior ofthe casing, cooling the armature results. f

.ofthe machine.l

the coininutator as it flowstlirough the' said hole. This is in contradistinction to the usual air current in a motor which passes through the casing without any deflection toward the coinmutator.

The ribs in the casing provide air passagesand after the 'air has passed through the fan it'flows out through recesses left in mounting the gear platero'nthe casing. The frontcapandgear plate are held in place by screws' 37, screwing `into the end ofthe casing inthe usual way.

'Referring next to the bearings for" the i Y various shafts, it will be noted that one of my objects is to provide a bearing which is spring sustained, but non-rotatable Aas a whole.

T hus. in -the back capthebearing is provided forthe inner Lend of the armature shaftfThis bearing isset 'into agsocketfl@ inthe back capand comprises an outer ring 41 held'inva slidable bushing 42, and an inner ring 43held on .the shaft.

The bushing 42 is dropped into the socket with acoiled spring'44 behind it and pressing against a shoulder 45 thereon. `A"pin.

46 thrust throughfrom the4 outside of jthe back cap engages a hole in the bushing and prevents it from revolving and thus being subject to Wear.'

.The shaft has a collar set over its end,v "which fits the socket in theY back cap' and bears ona felt wiper 48 to prevent escape of lubricantyf A cap, 49, on the end of the ,:shaft and held in p'lace by a screw 50, en-

to describe y all of the Agears mounted on the gear plate,-

ever, that the shaft bearing "arrangements A can be applied to the gearcase aswell as to shaft with equally beneficial 'Thus the pinionv 31u-on the end of the armature shaft meshes with a gear 52 carried on a shaft 53. This shaft is journaled ries. on it 'apinion'54 by means.y of which motion is transmitted vto the spindle gear The louter bearing ofthe shaft has a simple form of inner and outer raceways 55 and 56 with the usual balls and seats there- .in the gear plate and the back cap and carizo for, the inner race being held on the shaft by a cap 57 and screw 57EL and bearing against a shoulder onv the shaft. Thel outer race is driven into the socket of thelfront capto permanently remain in placewithofutVA rev? olution.

ln tl1e back.cap is mounted the inner bearing, in which vthe sliding-bushing e8 shafts.

mamar is provided and held against rotation by a pin 5U and resiliently forced to 'ard the body of the shaft by a spring GO. The inner bearing race 6l is held in place by a cap Gla on the shaft and also bears against the hub of the gear on this shaft. The outer-race 62 is driven tight into the bushing and by it is pressed toward the body of the shaft.

The advantage of this form of bearing for highly revolving shafts lies bothl in the 'simplicity of manufacture in which a care-- fully keyed or bolted fit of a bearing race into a cast socket of a casing is avoided, and in which the entire bearing is thrust by a spring into the proper position for taking the frictional strains, compensating for any ucar in the other bearing or for any slight defects in machining the shoulders on the Since the outer race carrier or bushing cannot revolve it does not rvear, but keeps in true iviththe socket, and the inner race being clamped on the shafts is free also from frictional Wear due to slipping on the same. l f

The bearings shown have their outer races driven tightly against revolution and their inner races clamped down tightly against rotation relative to theshafts on which they are mounted. .ln addition, they are open type bearings, and one of the great advantages of my sliding type bearingis that it permits the use of open type bearings onI motor shafts and the like. open type bearings are the easy assembly thereof, since to remove the shafts they need merely` be pulled out axially and can be thrust in Without adjustments in building up the device.

The advantages of Having thus described my invention,

what I claim as new and desire to secure -vvith a casing,` caps therefor, an armature' shaft supported therein, one` of said caps comprising a gearbox into which the said shaft extends, a fan' on the shaft to drauf7 air through the casing, said fan and gear box and casing being arranged so that the air forced by the fan forms J a compression pocket about the point, wherein the shaft extends into the gearbox in back of the fan, for the purpose described; A

2. The combination with a casing for an electric motor, a gear plate thereon serving as a shaft support, a motor shaft having bearing;` in said support,'a fan' on the shaft, said fan having a hub extending into the said bearing so as to form a compression chamber about its hub', the blades of thevfan being spaced away from the plate and the casing. and the casing and gear plate, at least one of them having air outlets located about the periphery of the said plate, as-and for the purpose described.

, 2l. ln an electric motor, the combination with a backcap and a casing to which it is secured, said parts formed with air ducts adjacent the connection between the cap and casing', a brush holder mounted in the casing and having an adjusting member, and a door inthe back cap located adjacent the brush holder adjusting member, whereby access may be had thereto, and the cap closed during operation of the motor, except for said ducts.

Geenen HENRY Porn. 

